Whats your avg MPG driving 70MPH?

[JimInMichigan]

Driving back from my dealership, bring home our new Mirage, I got 49.9 MPG doing 60mph, freeway was basically flat. Got on the next freeway to get home, I decided to drive 70mph. MPG was at 36.5, huge difference in my mind! Of course I understand the road was slightly uphill most of the time and a couple large hills, but I was still expecting 40MPH or higher.

Are not the 44MPG HWY federal specs considered at 70MPH? Surely they don't get those figures from driving 55, or do they?

[flotownj]

HWY is 55mph - Interstate is 70mph
EPA does not rate vehicles for the Interstate

[3dplane]

Don't forget this is after the car is up to the speeds shown! Accelerating not included!

BTW congrats on the new car! MPGs will get a little better with usage after the car is not brand new.

Also terrain,wind direction and traffic has a huge effect on MPGs. Not as huge as driving style though!

[f0k4l]

That chart is pretty much spot on. I can average 40MPG driving 75-80MPH, depending on grade. My car has 3k miles.

[MetroMPG]

Are not the 44MPG HWY federal specs considered at 70MPH? Surely they don't get those figures from driving 55, or do they?

FYI, none of the EPA tests are just "cruising" along at one speed or another. They're a mix of speeds.

Here's a plot showing two of the tests the Mirage was subjected to (on a lab dynamometer) to get its highway EPA rating:

"Highway" Test (note: max speed of 60 mph)



"High Speed" Test:



Full information about MPG testing:

http://www.fueleconomy.gov/feg/how_tested.shtml
and
http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

[Ares]

That chart is pretty much spot on. I can average 40MPG driving 75-80MPH, depending on grade. My car has 3k miles.

IIRC, this is accurate in my situation too. I was surprised to see that I get more MPG at a higher speed than slower speed.

[MetroMPG]

I was surprised to see that I get more MPG at a higher speed than slower speed.

I guarantee you don't, assuming you're in top gear at both speeds.

[Zero]

Mirage DE
5 Spd Manual
1200 ccm

Average: 40 mpg in stop and go traffic.
Best to date...51 mpg (~5,0/100 km).

[f0k4l]

Way home from work last night, had a good tail wind.

[mpaton]

I have seen 64 mpgUS at a steady 60mph, BUT this was at around 8000 ft altitude. Lower pumping losses.